CVE-2024-5508

Executive Summary

CVE-2024-5508 is a critical Out-Of-Bounds Write vulnerability in Luxion KeyShot Viewer, specifically during the parsing of KSP files. This flaw allows remote attackers to execute arbitrary code on the affected system, but requires user interaction—the victim must open a malicious KSP file or visit a malicious page. The vulnerability stems from insufficient validation of user-supplied data, leading to a write past the end of an allocated buffer. With a CVSS score of 7.8, this poses a significant risk to users of Luxion KeyShot Viewer, especially in environments where untrusted KSP files are processed. No public exploit code or patch details are currently available, but the vulnerability has been reported via ZDI-CAN-22267.

CVSS Breakdown & Threat Level

• CVSS Score: 7.8 (High)
• Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
• Attack Vector (AV): Local (AV:L) – The attacker must have local access or trick the user into opening a file.
• Attack Complexity (AC): Low (AC:L) – No special conditions required.
• Privileges Required (PR): None (PR:N) – No authentication needed.
• User Interaction (UI): Required (UI:R) – The victim must open the malicious file.
• Scope (S): Unchanged (S:U) – The vulnerability does not affect other components.
• Confidentiality (C): High (C:H) – Full data compromise possible.
• Integrity (I): High (I:H) – Full system control possible.
• Availability (A): High (A:H) – Potential denial of service or system crash.

Threat Level: High. Exploitation requires user interaction, but the impact is severe, allowing arbitrary code execution in the context of the current process.

Deep Dive & Mechanics

The vulnerability resides in the KSP file parsing routine of Luxion KeyShot Viewer. KSP files are project files used by KeyShot, a 3D rendering application. The specific flaw is an out-of-bounds write (CWE-787) that occurs when the parser processes a crafted KSP file. The lack of proper validation of user-supplied data allows an attacker to write data beyond the allocated buffer boundary. This can corrupt adjacent memory, leading to arbitrary code execution.

Technical Details:

• Root Cause: Insufficient bounds checking when copying data from the KSP file into a fixed-size buffer.
• Trigger: Opening a malicious KSP file (or visiting a page that triggers the viewer to open such a file).
• Exploitation: An attacker can craft a KSP file with a specially crafted field that causes the parser to write past the end of a buffer. This overwrites adjacent memory structures, potentially hijacking the execution flow.
• Impact: Arbitrary code execution in the context of the KeyShot Viewer process, which may have user-level privileges.

Vulnerable vs. Patched Code

Since no patch is available, a generic comparison is provided based on typical out-of-bounds write vulnerabilities.

Vulnerable Code (Conceptual):

void parse_ksp_field(char *buffer, size_t buffer_size, char *input) {
    // No bounds check
    memcpy(buffer, input, strlen(input));
}

Patched Code (Conceptual):

void parse_ksp_field(char *buffer, size_t buffer_size, char *input) {
    size_t input_len = strlen(input);
    if (input_len >= buffer_size) {
        // Handle error or truncate
        return;
    }
    memcpy(buffer, input, input_len);
}

The patched version adds a bounds check to ensure the input does not exceed the buffer size, preventing the out-of-bounds write.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Luxion KeyShot Viewer installed (any version).
• A crafted KSP file.

Exploitation Steps:

1. Craft Malicious KSP File: Use a hex editor or custom script to create a KSP file with an oversized field that triggers the out-of-bounds write. For example, a field that expects a 256-byte buffer but receives 512 bytes.
2. Deliver Payload: Embed shellcode or a ROP chain in the crafted field to achieve code execution.
3. Social Engineering: Convince the target to open the malicious KSP file (e.g., via email attachment or download link).
4. Execute: When the victim opens the file, the vulnerability triggers, executing the attacker's code.

Example Payload (Conceptual):

# Python script to generate a malicious KSP file
import struct

# Craft a buffer overflow payload
payload = b"A" * 256  # Fill buffer
payload += b"B" * 8   # Overwrite return address
payload += b"\x90" * 16  # NOP sled
payload += b"\xcc" * 4   # INT3 (breakpoint for testing)

# Write to KSP file
with open("malicious.ksp", "wb") as f:
    f.write(payload)

Note: No public exploit code is available. This is a conceptual example.

Blue Team (Defense)

Detection:

• Monitor for unusual KSP file activity, especially files from untrusted sources.
• Use endpoint detection and response (EDR) tools to detect out-of-bounds write attempts.
• Implement application whitelisting to prevent unauthorized execution.

Mitigation:

• Restrict opening KSP files from unknown sources.
• Use sandboxing or virtualized environments for processing untrusted files.
• Apply the principle of least privilege to the KeyShot Viewer process.

Indicators of Compromise (IOCs)

• File Hashes (SHA-256): (None available, but monitor for suspicious KSP files)
• Network Indicators: Connections to unknown IPs after exploitation (e.g., C2 traffic).
• Process Behavior: KeyShot Viewer crashing or exhibiting abnormal memory access patterns.
• Registry/File System: Unusual files written to disk by the KeyShot Viewer process.

Example IOC (Conceptual):

• File: malicious.ksp (SHA-256: e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855)
• Process: keyshot_viewer.exe spawning cmd.exe or powershell.exe.

Detection Engineering

YARA Rule

rule CVE_2024_5508_KSP_OutOfBoundsWrite {
    meta:
        description = "Detects malicious KSP files exploiting CVE-2024-5508"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2024-5508"
    strings:
        $magic = { 4B 53 50 } // "KSP" magic bytes
        $overflow = { 41 41 41 41 } // Pattern of 'A's indicating overflow
    condition:
        $magic at 0 and #overflow > 100
}

Sigma Rule

title: CVE-2024-5508 KeyShot Viewer KSP File Out-of-Bounds Write
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects attempts to exploit CVE-2024-5508 via malicious KSP files
author: Valters IT
date: 2025-04-10
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: '\keyshot_viewer.exe'
        CommandLine|contains: '.ksp'
    condition: selection
falsepositives:
    - Legitimate KSP files from trusted sources
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2024-5508 KeyShot Viewer KSP File Out-of-Bounds Write"; flow:to_server,established; content:"KSP"; offset:0; depth:3; content:"|41 41 41 41|"; distance:0; within:100; classtype:attempted-user; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable or restrict the use of Luxion KeyShot Viewer until a patch is available.
2. Educate users not to open KSP files from untrusted sources.
3. Implement application control to block KeyShot Viewer from executing if not needed.

Long-Term Fix:

• Await an official patch from Luxion. Monitor the vendor's website and security advisories.
• Consider using alternative 3D viewing software that is actively maintained.

Workarounds:

• Use a sandbox or virtual machine to open KSP files.
• Apply file reputation services to block known malicious KSP files.

Valters IT